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arXiv 1608.03403astro-ph.GA
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AGN反馈对早型星系星际介质的影响:低旋情形的二维流体动力学模拟

The Effect of the AGN Feedback on the Interstellar Medium of Early-Type Galaxies: 2D Hydrodynamical Simulations of the Low-Rotation Case

L. Ciotti, S. Pellegrini, A. Negri, J. P. Ostriker

摘要:

我们提出了2D流体动力学模拟的早期型星系包含中央大质量黑洞(MBHs)的演变,从年龄2 Gyr。该代码包含准确和物理一致的辐射和机械AGN风反馈,秒差距尺度的中央分辨率。质量输入来自恒星演化,能量输入包括Ia型和II型超新星以及恒星加热,恒星形成也包括在内。通过求解Jeans方程,建立了星系的真实的轴对称动力学模型。最低质量的模型(Mstar = 8 10^{10}Msun)发展了由SNIa加热维持的全球外流,最终热气体和新恒星的数量显着减少。在更大质量的模型中,核爆发持续到现在,伴随着核发射和气体(Lx)的大而频繁的波动。每次爆发持续约10^{7.5}年,在此期间(r < 2-3 kpc)冷的流入和热的流出气体相共存。气体的Lx-T关系与本地星系的Lx-T关系相匹配。活动星系核的活动对恒星的形成产生正反馈。大约一半的总质量损失被回收到新的恒星(DeltaMstar)中,只有约3%的质量损失被吸积在MBH上,其余的被从星系中喷射出来。排出的气体质量与进入新恒星的气体质量之比,即负载因子,约为0.6。更圆的星系形状导致更大的最终MBH质量,DeltaMstar和Lx。几乎所有的时间都花在非常低的核光度上,然而总能量的四分之一是在爱丁顿比> 0.1时发射的。活动星系核活动的占空比约为4%。

英文摘要:

We present 2D hydrodynamical simulations for the evolution of early-type galaxies containing central massive black holes (MBHs), starting at age 2 Gyr. The code contains accurate and physically consistent radiative and mechanical AGN wind feedback, with parsec-scale central resolution. Mass input comes from stellar evolution; energy input includes Type Ia and II supernova and stellar heating; star-formation is included. Realistic, axisymmetric dynamical models for the galaxies are built solving the Jeans' equations. The lowest mass models (Mstar = 8 10^{10}Msun) develop global outflows sustained by SNIa's heating, ending with a significantly lower amount of hot gas and new stars. In more massive models, nuclear outbursts last to the present epoch, with large and frequent fluctuations in nuclear emission and from the gas (Lx). Each burst last ~ 10^{7.5} yr, during which (for r < 2-3 kpc) cold, inflowing, and hot, outflowing gas phases coexist. The Lx-T relation for the gas matches that of local galaxies. AGN activity causes positive feedback for star formation. Roughly half of the total mass loss is recycled into new stars (DeltaMstar), just ~ 3% of it is accreted on the MBH, the remainder being ejected from the galaxy. The ratio between the mass of gas expelled to that in to new stars, the load factor, is ~0.6. Rounder galaxies shapes lead to larger final MBH masses, DeltaMstar, and Lx. Almost all the time is spent at very low nuclear luminosities, yet one quarter of the total energy is emitted at an Eddington ratio > 0.1. The duty-cycle of AGN activity approximates 4% (Abridged).

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